Ethernet

general Linux commands

ifconfig -a

• attivare la scheda di rete eth0 (senza script di ifup/ifdown)

ifconfig eth0 up

• Chiedere in broadcast un indirizzo ip su eth0 (!!!)

dhclient eth0

• Sapere se hai problemi con la scheda (il NIC)

# tail -50 /var/log/messages |grep -A4 eth0
NETDEV WATCHDOG: eth0: transmit timed out
Mar 26 14:21:39  kernel: eth0: transmit timed out, tx_status 00 status e000.
Mar 26 14:21:39 kernel:   diagnostics: net 0cf2 media 8880 dma 000000a0 fifo 0000
Mar 26 14:21:39 kernel:   Flags; bus-master 1, dirty 1048374(6) current 1048390(6)
Mar 26 14:21:39 kernel:   Transmit list 16c7f5c0 vs. d6c7f5c0.

• scanneriz1zare una rete privata:

for a in `seq 1 254`; do echo -n -e "\r   $a   ";ping -c1 192.168.1.$a|grep "bytes from "; done

host scanning

• nmap is the master tool, then everything follows.

nmap <host>

• a more specific scan, suggested from [Gavin Pearce]

nmap -sS -p0-65535 -P0 -T4 --osscan_limit --osscan_guess --host_timeout 15m --max-retries 0 --min_parallelism 100 --max_parallelism 500 -O -oX -V <host>

Cisco

• para conectar un host directo a un puerto de un router (Cisco)

cisco-6500#
cisco-6500#conf t
cisco-6500(config)#int gi3/44
cisco-6500(config-if)#spanning-tree port ?
 port-priority  portfast
cisco-6500(config-if)#spanning-tree portfast ?
 disable  Disable portfast for this interface
 trunk    Enable portfast on the interface even in trunk mode
 <cr>
cisco-6500(config-if)#spanning-tree portfast